• Title, Summary, Keyword: STS Content

Search Result 79, Processing Time 0.029 seconds

A Study on Science Teachers' Perceptions of the 6th High School Science Curriculum and Their Practices (제6차 고등학교 과학 교육과정과 실천에 대한 과학 교사의 인식 조사)

  • Noh, Tae-Hee;Kwon, Hyeok-Soon;Kim, Hye-Kyoung;Park, Sung-Jae
    • Journal of The Korean Association For Science Education
    • /
    • v.20 no.1
    • /
    • pp.20-28
    • /
    • 2000
  • We examined how science teachers in academic high schools perceived the 6th science curriculum and how they practiced under the curriculum. A nationwide survey was administered to obtain the responses from 402 teachers of 135 high schools. Most thought that the main themes of curriculum revision were well-embedded in the 'objectives', and that the 'content and content structure' were proper. However, they thought that the 'objectives' were not stated explicitly enough to develop teaching materials and to improve actual teaching and evaluation, and that some statements in the sections of 'method' and 'evaluation' were not proper if considered actual teachers' ability to teach inquiry and educational facilities. Many teachers also felt that the information about the curriculum was not sufficiently included at in-service teacher training programs, and that students' knowledge, attitude, and problem solving ability were not enhanced. Only few teachers were found to apply the STS approaches, reconstruct lessons, vary the structure of learning group, and develop evaluation tools with their colleagues. The lack of the practices was explained by entrance-examination-centered instruction and assessment, poor educational facilities, and lack of innovative teaching materials.

  • PDF

Identification and characterization of QTLs and QTL interactions for Macro- and Micro-elements in rice (Oryza sativa L.) grain

  • Qin, Yang;Kim, Suk-Man;Sohn, Jae-Keun
    • Journal of Plant Biotechnology
    • /
    • v.35 no.4
    • /
    • pp.257-263
    • /
    • 2008
  • Improvement of the macro- and micro-elements density of rice (Oryza sativa L.) is gradually becoming a new breeding objective. In this study, the genomic regions associated with potassium, calcium, magnesium and iron content in rice grain were identified and characterized by using a doubled haploid (DH) population. Fifty-six simple sequence repeat (SSR) and one hundred and twelve sequence tagged site (STS) markers were selected to construct the genetic linkage map of the DH population with a full length of 1808.3cM scanning 12 rice chromosomes. Quantitative trait loci (QTLs) were detected, and QTL effects and QTL interactions were calculated for five traits related to macro- and micro-elements in the DH population from a cross between 'Samgang' (Tongil) and 'Nagdong' (Japonica). Twelve QTLs were located on five chromosomes, consisting of two QTLs for potassium, three QTLs for calcium, two QTLs for magnesium, one QTL for iron content and four QTLs for the ratio of magnesium to potassium (Mg/K). Among them, qca1.1 was detected on chromosome 1 with an LOD value of 8.58 for calcium content. It explained 27% of phenotype variations with increasing effects from 'Samgang' allele. Furthermore, fifteen epistatic combinations with significant interactions were observed on ten chromosomes for five traits, which totally accounted for 4.19% to 12.72% of phenotype variations. The screening of relatively accurate QTLs will contribute to increase the efficiency of marker-assisted selection (MAS), and to accelerate the establishment of near-isogenic lines (NILs) and QTL pyramiding.

An Analysis of Inquiry Activities in Chemistry II Textbook by Using 3-Dimensional Analysis Framework (3차원 분석틀을 이용한 화학II 교과서의 탐구활동 분석)

  • Seok Hee Lee;Yong Keun Kim;Seong Bae Moon
    • Journal of the Korean Chemical Society
    • /
    • v.47 no.4
    • /
    • pp.391-400
    • /
    • 2003
  • This study was performed the analysis of seven kinds of the hight school chemistry II textbooks based on the 6th curriculum. Particularly, inquiry activity part was analyzed by the three dimension framework which consists of inquiry content dimension, inquiry process dimension and inquiry context dimension. In the analysis of the inquiry content dimension of inquiry activities, the total number of themes in seven kinds of textbook was 212. And the number of inquiry activities in seven kinds of textbook was diverse: A textbook had 28, B textbook 25, C textbook 31, D textbook 35, E textbook 31, F textbook 29 and G textbook 33. As for the avaerage number of inquiry activities of each chapter, chapter I "Material Science" is 3.00(9.91${\%}$), chapter II "Atomic Structure and Periodic Table" 4.57(15.1${\%}$), chapter III "Chemical Bonding and Compound" 6.86(22.6${\%}$), chapter IV "State of Matter and Solution" 7.00(23.1${\%}$), chapter V "Chemical Reaction" 8.86(29.2${\%}$). For the analysis of inquiry process dimension, it follows in the order of 'observation and measuring (66.7${\%}$)', 'Interpreting data and formulating generalizations (26.5${\%}$)', 'seeing a problem and seeking ways to solve it (4.1%)', and 'building, testing and revising the theoretical model (2.7${\%}$)'. As for the analysis of the inquiry context dimension, the scientific context occupied 90.5${\%}$, the individual context 4.3${\%}$, the social context 0.9${\%}$, and the technical context 4.3${\%}$. It shows that the proportion of STS(Science-Technology-Society) related contents in inquiry activities was only 9.5${\%}$.

The Stress Corrosion Cracking Resistance of Heat Treated STS304 Stainless Steel Welded Metal (304 스테인리스강 용접금속의 열처리에 따른 응력부식균열)

  • Cho, D.H.;Kim, H.R.;Nam, T.W.
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.9 no.1
    • /
    • pp.34-44
    • /
    • 1996
  • Austenite stainless steel was produced by arc welding with current 650A, voltage 50V and welding speed 10cm/min. It was post-welded and then heat treated at $1,050^{\circ}C$ for 120min. And then it was immersed in water or in air. The microstructural changes, ferrite contents, mechanical properties, and stress corrosion cracking(SCC) were investigated. The SCC was studied in 42wt% boiling $MgCl_2$($140^{\circ}C$) under the constant stress using SCC elongation curve. The results showed that; 1. The as-welded spedimen seemed to increase ${\delta}$-ferrite content largely, and revealed continuous network of lathy and vermicular type. The post-welded heat treatment changed the morphologies of ferrite from continuous type to island type. 2. The as-welded, air and water quenched specimens had the ${\delta}$-ferrite content 9.7%, 3.2% and 2.1% respectively. We also showed that ${\delta}$-ferrite was Cr-rich and Ni-poor by EPMA. 3. The time of failure on the SCC was measured and it was used for corrosion elongation curve. The condition of SCC was investigated under $35kgf/mm^2$ load and the results were as follows; 4. The intergranullar cracking by stress corrosion was most distinct in weld metal while the transgranular cracking occurred in the air cooled specimen.

  • PDF

Effects of Emulsified Sausage Supplemented with Ginseng Saponin on Lipid Metabolism in Rat

  • Shim, Kwan-Seob
    • Food Science of Animal Resources
    • /
    • v.30 no.4
    • /
    • pp.582-589
    • /
    • 2010
  • The current study was designed to assess the effects of emulsified sausage supplemented with ginseng saponin on lipid metabolism by applying a rat model. Four groups of 8 rats (5 wk old) were each allocated one of 4 treatments: basal feed (C), and basal feed with 20% sausage powder containing 0% (S0), 2% (S2) and 4% (S4) ginseng saponin. The experiment was conducted for 4 wk. The results did not differ among the treatments with different amounts of sausage (ST), but daily feed intake (p<0.01) and feed conversion (p<0.001) were significantly increased in STs compared to C. Both total serum cholesterol and triglyceride concentrations were significantly (p<0.001) reduced, by 45 and 46%, and 48 and 46%, in S2 and S4, respectively, compared to S0. In the liver, the total cholesterol level was dramatically (p<0.05) decreased according to increasing sausage powder levels. In particular, S4 showed approximately 14% reduction compared to S0 (p<0.05). Liver triglyceride content also showed a similar tendency, where S2 and S4 resulted in 7% and 31% reduction. With regard to fatty acid composition in the liver tissues, palmitic acid (16:0), oleic acid (18:1), eicosanoic acid (20:1), and eicosatrienoic acid (20:3) did not differ among the STs, whereas both linoleic acid (18:2) (p<0.01) and linolenic acid (18:3) (p<0.001) showed significant increases in S2 compared to S0. The current data demonstrated that emulsified sausages supplemented with ginseng saponin effectively reduce total cholesterol and triglyceride concentrations in the serum and liver, and increase unsaturated and essential fatty acid in the liver. These data collectively imply that the sausage improved the overall lipid profile in a rat model, and can be further generalized to the result that emulsified sausage can improve lipid metabolism depending on the products' formula.

A Study on the Oxidation Behavior of Metal Materials Applicable to Oxidizer Rich Pre-Combustor (산화제 과잉 연소기에 활용 가능한 금속재료의 산화 거동에 관한 연구)

  • Shin, Donghae;Yu, Isang;Shin, Minku;Ko, Youngsung;So, Younseok;Han, Yeoungmin
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.23 no.2
    • /
    • pp.118-125
    • /
    • 2019
  • Metals exposed to high temperature/high pressure/oxidant excess environment of an oxygen excess pre-combustor may undergo rapid oxidation. In this study, the test facility to simulate the high temperature/high pressure/oxidant excess environment was constructed and the oxidation resistance evaluation was carried out for various metal materials. As a result, the discoloration of the metallic materials, the change in the surface roughness and the peeling of the metal surface were observed, and the weight change was also observed. The resulst showed that oxidation-resistant coating of a metal material of the combustor is indispensably required, and the use of XM-19, which has the highest content of Cr and Ni, is expected to provide more structural stability.

Effect of Si Addition on the Corrosion Resistance of Diamond-Like Carbon (DLC) Films

  • Kim, Woo-Jung;Kim, Jung-Gu;Park, Se-Jun;Lee, Kwang-Ryeol
    • Corrosion Science and Technology
    • /
    • v.4 no.6
    • /
    • pp.226-230
    • /
    • 2005
  • Si incorporated diamond-like carbon (Si-DLC) films ranging from 0 to 2 at.% contents were deposited on STS 316L substrates for orthopedic implants by means of r.f. plasma-assisted chemical vapor deposition (r.f. PACVD) technique, using mixtures of benzene ($C_6H_6$) and silane ($SiH_4$) as the precursor gases. This study provides the reliable and quantitative data for assessment of the effect of Si incorporation on corrosion property in the simulated body fluid environment through the electrochemical test. It was found that corrosion to resistance of Si-DLC coatings with increasing Si content are improved owing to high $sp^3$ bonding.

The Comparison of Characteristic between Electron Beam Welding and Narrow-gap TIG welding with 316LN Stainless Steel (스테인레스강 316LN의 전자빔용접과 협개선TIG 용접특성 비교)

  • Jeong, In-Cheol;Kim, Yong-Jae;Lee, Gyeong-Un;Sim, Deok-Nam
    • Proceedings of the KWS Conference
    • /
    • /
    • pp.82-84
    • /
    • 2005
  • Among the advanced welding processes which are superior to conventional process, Electron beam welding and Narrow-gap TIG welding are most prospective in being applicable for the heavy industry field. With STS316LN, which is high strengthened austenitic stainless steel, the characteristic evaluation for these welding processes was carried out through the mechnical tests and property analyses. For the tensile strength EBW is better while in reverse for the yield strength. In Narrow-gap TIG the distribution of hardness values has some deviation according to the thickness direction while EBW has a tendency of a litter high hardness values in weld metal. After EB welding brings the reduction of nitrogen content, in TIG welding weld metal depends on the contents of welding material. Both processes have almost austenitic structure, but weld metal of EBW is also shown terrific structure

  • PDF

Anodic Polarization Properties of Ti-Zr-Pd Based Alloys for Biomedical Applications (생체용 Ti-Zr-Pd계 합금의 양극분극특성)

  • Jung, Jong-Hyun
    • Journal of Technologic Dentistry
    • /
    • v.23 no.1
    • /
    • pp.21-30
    • /
    • 2001
  • For biomedical applications. Ti-X%Zr-Y%Pd(X: $10{\sim}20$, Y:0.2 or 0.4) based alloys not containing harmful Al and V were newly designed, and polarization curves for their alloys were measured at $37^{\circ}C$ in 5% HCl solution in order to understand effects of Zr on the corrosion. From the results of anodic polarization behavior, it was found that the corrosion resistance increased with increasing Zr content. The results show their potential to develope Ti-based alloys for biomedical materials. The Ti-20%Zr-0.2%Pd alloy shows excellent corrosion resistance and was superior to those of the Ti. Ti-6%Al-4%V ELI alloy, Co-30%Cr-6%Mo alloy and STS 316L stainless steel.

  • PDF

Microstructural Changes during Tempering Treatment of Nitrogen-permeated STS 410 and 410L Martensitic Stainless Steels (질소침투 열처리한 STS 410 및 410L 마르텐사이트계 스테인리스강의 템퍼링에 의한 조직변화)

  • Lee, Hea Joeng;Kong, Jung Hyun;Lee, Hae Woo;Yu, Dea Kyung;Kang, Chang Yong;Sung, Jang Hyun
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.20 no.2
    • /
    • pp.84-93
    • /
    • 2007
  • Microstructural changes during tempering at the temperature range of $300^{\circ}C{\sim}700^{\circ}C$ for the nitrogen-permeated STS 410 and 410L martensitic stainless steels has been investigated. After nitrogen permeation at temperature between 1050 and $1150^{\circ}C$, the surface layer appeared fine $Cr_2N$ of square and rod types in the martensite matrices. Hardness of the nitrogen-permeated surface layer represented 680Hv and 625Hv, respectively, for 410 and 410L steels. It is considered that the fine homogeneously dispersive effect of precipitates by nitrogen caused the increased hardness. Due to the counter current effect of carbon from interior to surface during nitrogen diffusion from surface to interior, the 0.1%C alloyed 410 steel showed the low nitrogen content of 0.025% compared with 0.045% of 410L steel at the distance of $100{\mu}m$ from the surface. Tempering of nitrogen-alloyed 410 and 410L showed the maximum hardness at $450^{\circ}C$. This maximum hardness was considered to be the secondary hardening effect of very fine carbide and nitride. The decrease in hardness at $700^{\circ}C$ was the softening effect of the matrix due to the precipitation of many needle-shaped $Cr_2N$ for 410 steel and the precipitation of coarse nitride of $Cr_2N$ in line with the spherical precipitates with directionality for 410L steel. For 410 steel, the corrosion resistance of nitrogen permeated surface in the solution of 1 N $H_2SO_4$ were nearly unchanged, however the superior corrosion resistance was obtained for nitrogen permeated 410L steel compared to the solution annealed condition.